Dark Shaman and Thok are terribly designed encounters and whoever designed them should feel bad. Galakras and Nazgrim are annoying as well because of its unnecessary length.
Blackfuse, Paragons, Sha of Pride, and Malkorak were neat fights though.
I've began to notice a trend with Blizzard where instead of shorter chaotic encounters around the 5 minute mark like Malkorak, they've begun to make a lot of 9 minute survival clusterfucks with backloaded mechanics and unnecessarily long bullshit phases. Throne of Thunder had a lot of these as well. Stop it.